Haeckel maintained not only that all vertebrate embryos evolved from a common ancestor, but also that in their development ( "ontogeny") they replay ( "recapitulate") their evolutionary history ( "phylogeny").

It turns out that DNA interacts in entirely chance ways during the course of ontogeny -- the development of the embryo -- based simply on how the chromosomes cross and fold back on themselves and one another.

'This starlit world is still the world, presumably, and every part of it, including humankind, is unchanged in its nature still embodying the history that is also its ontogeny. The Absence of Mind by Marilynne Robinson 2010.